1. Technical Field
Aspects of the present invention relate to an information processing device having a watermark printing function.
2. Related Art
Printer drivers having a watermark printing function are widely used. Through the watermark printing function, data of a watermark image (e.g., watermark letters) can be added to data of a main image (e.g., a document) to be printed. For example, an indication “Confidential”, “Important”, “Urgent” or “No Copy” is added on a document to be printed so as to attract the attention of readers of the document. An example of a printing device having the watermark printing function is disclosed in Japanese Patent Provisional Publication No. HEI 11-298717.
In general, the watermark printing function includes a background mode and a transparent mode. FIGS. 9B and 9C illustrate examples of an overlap image of a main image 10M and a watermark image 10W (see FIG. 9A) printed in the background mode and transparent mode, respectively. In the background mode, the main image 10M is written on the watermark image 10W (see FIG. 9B). Since in this case the watermark image 10W is covered with the main image 10M, there are cases where readers of the main image (e.g., a document) hardly recognize the watermark image 10W (i.e., a word “Copy”) depending on the size of the watermark image 10W.
As shown in FIG. 9C, in the transparent mode, data of the watermark image 10W undergoes a process for giving transparency to the watermark image 10W, and thereafter the watermark image data which has undergone the transparency process is overlaid on the data of the main image 10M. Since the watermark image has undergone the transparency process, a reader of the overlap image shown in FIG. 9C is able to recognize both of the main image and the watermark image in an overlap portion between the main image and the watermark image. However, in the transparent mode, a part of the watermark image not overlapping with the main image also undergoes the transparent process. Therefore, readers of the overlap image shown in FIG. 9C may feel that the entire watermark image is light and difficult to recognize.